黑龙江鸡西地区晚古生代浅变质岩地球化学特征及构造环境

Geochemistry of Late Paleozoic epimetamorphic rocks in Jixi of Heilongjiang and its structural setting

鸡西地区晚古生代浅变质岩系从泥盆纪至二叠纪均有不同程度出露,岩石地球化学特征显示富硅(SiO2一般为71.46×10-2～81.30×10-2)、高钾(K2O/Na2O=1～13)、贫钛(TiO2=0.05×10-2～0.6×10-2);稀土元素以轻稀土富集、负铕异常和重稀土平坦为特征;微量元素富集相容元素,Sr/Ba<1。该期浅变质岩系原岩以沉积岩中的杂砂岩为主,同沉积过程中伴有较强的火山活动。各种岩石化学特征参数显示,浅变质岩系形成于活动大陆边缘裂陷沉积盆地。

The epimetamorphic rock series were outcropped at different degrees from Devonian to Permian of Jixi area. The lithogeochemical characteristics indicate the rocks are enriched in SiO2 （71.46 × 10^-2 -81.30 × 10^-2） , and high in K （K2O/Na2O = 1 - 13）, with low TiO2 （0. 05 × 10^-2 -0. 6 × 10^-2） in content. The REE pattern is characterized by LREE in concentration, negative Eu-anomaly and fiat HREE. The trace elements enrich consistent elements with Sr/Ba 〈 1. Apogrite predominates in the protolith of the series. There took place strongly volcanic activity during syndeposit process. The various lithogeochemical parameters show that the epimetamorphic series were formed in the rift sedimentary basin on active continental margins.